21675551 has 4 divisors (see below), whose sum is σ = 21692712. Its totient is φ = 21658392.

The previous prime is 21675529. The next prime is 21675553. The reversal of 21675551 is 15557612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21675551 - 2¹⁴ = 21659167 is a prime.

It is a super-2 number, since 2×21675551² = 939659022307202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21675553) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6521 + ... + 9266.

It is an arithmetic number, because the mean of its divisors is an integer number (5423178).

Almost surely, 2^21675551 is an apocalyptic number.

21675551 is a deficient number, since it is larger than the sum of its proper divisors (17161).

21675551 is a wasteful number, since it uses less digits than its factorization.

21675551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17160.

The product of its digits is 10500, while the sum is 32.

The square root of 21675551 is about 4655.7009139334. The cubic root of 21675551 is about 278.8196528066.

The spelling of 21675551 in words is "twenty-one million, six hundred seventy-five thousand, five hundred fifty-one".